You can specify a canonical URL in two ways:
[LIST]
[*][B]Add a rel="canonical" link to the <head> section of the non-canonical version of each HTML page.[/B] To specify a canonical link to the page [URL]http://www.example.com/product.php?item=swedish-fish[/URL], create a <link> element as follows:
<link rel="canonical" href="http://www.example.com/product.php?item=swedish-fish"/>
[*]Copy this link into the <head> section of all non-canonical versions of the page, such as [URL]http://www.example.com/product.php?item=swedish-fish&sort=price[/URL].
If you publish content on both [URL]http://www.example.com/product.php?item=swedish-fish[/URL] and [URL]https://www.example.com/product.php?item=swedish-fish[/URL], you can specify the canonical version of the page. Create the <link> element:
<link rel="canonical" href="http://www.example.com/product.php?item=swedish-fish"/>
[*]Add this link to the <head> section of [URL]https://www.example.com/product.php?item=swedish-fish[/URL].
[*][B]Indicate the canonical version of a URL by responding with the Link rel="canonical" HTTP header.[/B] Adding rel="canonical" to the head section of a page is useful for HTML content, but it can't be used for PDFs and other [URL="https://support.google.com/webmasters/answer/answer.py?answer=35287"]file types indexed by Google Web Search[/URL]. In these cases you can indicate a canonical URL by responding with the Link rel="canonical" [URL="http://en.wikipedia.org/wiki/List_of_HTTP_header_fields"]HTTP header[/URL], like this (note that to use this option, you'll need to be able to configure your server):
Link: <http://www.example.com/downloads/white-paper.pdf>; rel="canonical"
[/LIST]

It's only right if it is on the home page of xyz.com... The syntax is proper, but the correctness depends if the canonical URL is the most appropriate URL for the content being displayed... If you used your example on all the pages of xyz.com then it would be incorrect for all pages but 1.

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